Restylane persistent for 23 months found during Mohs micrographic surgery: a source of confusion with hyaluronic acid surrounding basal cell carcinoma.

[BACKGROUND] Restylane (Q-Med, Uppsala, Sweden), a hyaluronic acid (HA) that is microbiologically produced and then cross-linked, is becoming popular as a dermal filler for improvement of facial lines and wrinkles. However, it is currently believed that the clinical and histologic persistence of this filler is from 6 to 9 months. We recently encountered Restylane in tissue where it had been implanted 23 months prior to removal of a basal cell carcinoma (BCC) on the lip, and its presence caused some confusion with HA that surrounds BCC nests.

[OBJECTIVE] To show and to contrast the histologic dermal appearance of Restylane and its metachromatic staining characteristics with toluidine blue from those of HA that surrounds BCC nests.

[METHOD] Toluidine blue staining at pH 7.07 was performed on excised tissue containing Restylane and BCC on the upper lip.

[RESULTS] Restylane appeared as reddish-purple amorphous masses, whereas the HA that frames BCC nests appeared redder and more well defined.

[CONCLUSION] The amorphous metachromatic reddish-purple color staining of Restylane with toluidine blue is due to its HA content. This staining pattern should be differentiated from the well-defined red color of HA that normally borders BCC nests. Restylane may persist in the dermis as long as 23 months after implantation.